Risk of lung cancer among masons in Iceland

To estimate the risk of gastrointestinal cancer and lung cancer in a cohort of masons exposed to cement and hexavalent chromium by a follow up in the Icelandic Cancer Registry.

The cohort, 1172 men, was defined as those who had served their apprenticeship and were fully licensed as masons (cement finishers) in Iceland, were born after 1880 and were alive in 1955. The men were exposed to an aerosol of wet concrete, particularly when spraying. According to the analyses of urinary chromium the masons were exposed to hexavalent chromium. A computer file on masons was record linked to the Cancer Registry by making use of the personal identification numbers. Expected cancer incidence was calculated on the basis of number of person-years for each five-year age category during the individual calendar years of the study period and multiplied by the specific incidence for cause and calendar year for men in Iceland provided by the Cancer Registry.

The standardised incidence ratio (SIR) for all cancers was 1.13 in the total cohort and 1.33 when allowance was made for 30 years to elapse before starting to count person years of risk. The risk for gastrointestinal cancers was not increased. The SIR for lung cancer was 1.69 in the total cohort and 1.77 when a lag of 30 years was included. The SIR for lung cancer among those born in 1920 or later was 1.86. Results from a postal questionnaire showed that fewer masons had never smoked and more masons had stopped smoking than the controls from the general population.

The increased risk of lung cancer among the masons may be related to their work. The exposure information, although limited, supports the suggestion that hexavalent chromium in the cement may be the causal link, as information on the smoking habits indicate that the control for this important possible confounder is adequate.